The subject matter disclosed herein relates to an ultrasonic imaging apparatus which acquires tomographic image of a subject to which a contrast agent is administered.
In an ultrasonic imaging apparatus, examinations using contrast agents are frequently performed. The contrast agents administered to a subject circulate in the blood and permeate through within a tissue. These contrast agents are projected as high brightness areas in the case of a tomographic image acquired from the ultrasonic imaging apparatus and yield information useful clinically.
The contrast agents are made up of micro bubbles of a few μm or so. A plurality of types different in property exist as the contrast agents. An initially-developed contrast agent (Levovist) has destroyed bubbles by applying ultrasound of high MI (Mechanical Index) and effected imaging on strong reflected ultrasound developed upon destruction thereof. This contrast agent is observed on a tomographic image only at the instant when ultrasound of high sound pressure is applied. Thereafter, the contrast agent loses a contrast function.
On the other hand, there has recently been developed a contrast agent (Sonazoid) that does not destroy bubbles and maintains a contrast function even though low MI ultrasound is applied repeatedly. In the present contrast agent, the manner in which the contras agent lying within a subject changes with time, can be repeatedly projected and observed on a tomographic image displayed in real time, by once-contrast agent administration.
The contrast agent has the property of being englutted through Kupffer cells of a tissue portion from within the blood vessels. It has also been practiced to observe the contrast agent that permeates into the tissue portion. In the present observation, progress is observed over a long period of time as compared with the case in which the contrast agent migrates into the blood vessels.
In this long-duration examination, it is practiced to locate a treatment chamber for administering the contrast agent to the subject and an examination chamber for imaging the subject in different positions respectively and observe a contrast agent permeation process partly at pivotal points segmented in terms of time. In this case, an operator repeatedly performs a similar examination on the same subject during a plurality of inspection or examination times segmented in terms of time, using an ultrasonic imaging apparatus. The operator also performs other examinations during intervals between the examination times to enhance the availability of the ultrasonic imaging apparatus.
Here, the time that elapses since the administration of the contrast agent to the subject has an important meaning clinically upon the contrast agent examination. Therefore, a timer started up upon administration of the contrast agent exists in the ultrasonic imaging apparatus to measure the above-described elapsed time.
However, it was not easy to control or manage the time that elapses from the administration of the contrast agent to the subject. That is, when the treatment chamber for administering the contrast agent and the examination chamber for imaging the subject are different from each other, the subject is carried or conveyed to the examination chamber after the contrast agent has been administered to the subject in the treatment chamber, and the start-up of the timer for measuring or counting the elapsed time of the contrast agent is performed with respect to the ultrasonic imaging apparatus in the examination chamber. Since the time at which the contrast agent is administered to the subject, and the time taken to start up the timer are different from each other in this case, the elapsed time does not indicate the time that elapses immediately after the administration of the contrast agent to the subject.
When the process of permeation of the contrast agent into the subject is observed partly at the pivotal points segmented in terms of time, there exists a case in which contrast agent examinations for plural subjects are performed on a simultaneous promotion basis using one ultrasonic imaging apparatus. In this case, the ultrasonic imaging apparatus needs to simultaneously manage elapsed times subsequent to the start of administration to the plural subjects. However, this puts a large burden on the operator. It is not easy to put into practice. Although it is also considered that a plurality of timers are provided in the ultrasonic imaging apparatus, it is not efficient if it is considered that the number of timers required upon imaging is only one.
In terms of these, it is of importance of how an ultrasonic imaging apparatus capable of reducing a burden imposed on an operator and measuring an elapsed time from the administration of a contrast agent to a subject without fail even when a contrast agent examination has a complex process, is realized.